Cutting Knife For Slitting Metal Foil

Abstract

A rotatable cutting knife for use in a machine for slitting a moving web of metal foil, the cutting knife cooperating with a driven backup knife to slit the foil by a shearing action. The cutting knife has a concave configuration and is supported by a structure affording adjustments of the cutting knife with respect to the backup knife, thereby reducing the overlaping of the knives required to shear a particular foil and minimizing the possibility of the cutting knife overriding the backup knife.

Description

BACKGROUND OF THE INVENTION

Various types of slitting or shearing apparatus are available for continuously slitting metal foil or metal laminates in roll form. The cutting knife has a thickness of 0.010-0.020 inch and overlaps an edge formed on a power-driven backup knife, thereby to shear a web of foil moving between the two knives. Heretofore, it has been necessary to provide a knife overlap to some 0.030 inch in order to provide the shearing action and to prevent the cutting knife from overriding the edge of the backup knife, particularly in high speed slitting machines. This amount of overlapping of the knives cannot be tolerated in a machine for slitting relatively thin foil of a soft metal as, for example, soft aluminum foil having a thickness of the order of 0.002 inch. The excessive overlapping of the knives produces a curling over of the edges of the slit foil which results not only in uneven wound rolls but also, limits the applications for which the slit foil may be used. Furthermore, in present slitting machines, a plurality of cutting knives are supported in operative position with respect to associated backup knives by a common knife beam which is adjustable in one direction to permit the initial feeding of the foil between the knives and in the opposite direction to set the cutting knives in overlapping relationship to the edges of the backup knives. Such arrangement requires grinding the cutting knives to a precise diameter. Also, an adjustably mounted knife beam is subject to vibration during machine operation, which requires a greater than necessary amount of knife overlap to assure a positive shearing action and to prevent the cutting knives from riding up onto the peripheral surfaces of the associated backup knives.

Cutting knives constructed and arranged in accordance with this invention overcome the shortcomings of existing arrangements. The cutting knives are supported on the knife beam by individual structures and the cutting knives are individually adjustable with respect to the associated backup knives, thereby permitting a close control of knife overlap. Also, the cutting knives are mounted on individual backing discs in a manner which substantially eliminates the possibility of a cutting knife overriding the backup knife even though the knife overlap is set to a minimum value.

ABSTRACT OF THE INVENTION

A cutting knife is stressed into a bowed condition by securing the knife in face contact with a tapered surface formed on a rotatable backing disc. The backing disc and its supporting bearings are pivotally secured to a structure which is attachable to a knife beam, said structure including means for the adjustment of the knife in two planes, thereby to set the knife in proper operating position with respect to an associate backup knife. The structure also carries means for displacing the cutting knife relative to the backup knife for the purpose of threading a metal foil between the two knives and thereafter returning the knife to its initially established operative position.

An object of this invention is the provision of an improved cutting knife particularly adapted for slitting thin metal foil.

An object of this invention is the provision of foil slitting apparatus of the class having a cutting knife cooperating with a backup knife, which apparatus includes means for setting and maintaining a minimum overlapping of the two knives required to slit metal foil of a given thickness.

An object of this invention is the provision of a cutting knife for slitting metal foil, which cutting knife is secured in face engagement with a tapered surface formed on a rotatably mounted backing disc.

An object of this invention is the provision of a cutting knife for slitting metal foil, said knife being freely rotatable and supported for pivotal movement by a structure which is attachable to the knife beam of a slitting machine, said structure including means affording adjustment of the cutting knife in two planes.

The above-stated and other objects and advantages of the invention will become apparent from the following description when taken with the accompanying drawings. It will be understood however, that the drawings are for purposes of illustration and are not to be construed as defining the scope or limits of the invention, reference being had for the latter purpose to the claims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings wherein like reference characters denote like parts in the several views:

FIG. 1 is a top plan view of a cutting knife assembly made in accordance with this invention, the upper bearing housing being broken away to show the bearings and the shaft to which the knife is secured;

FIG. 2 is a left side elevational view thereof;

FIG. 3 is a right side elevational view with the lower bearing housing broken away to show the pivotal mounting of the knife;

FIG. 4 is a front end elevational view; and

FIG. 5 is a fragmentary, horizontal cross-sectional view drawn to an enlarged scale and showing the cutting knife in operative position with respect to the backup knife.

DESCRIPTION OF PREFERRED EMBODIMENTS

Reference now is made particularly to FIGS. 2 and 3 showing the dove-tail mounting bar 10 by means of which the knife assembly is attachable to the fixed knife beam 11 carried by a cross member 12 of a slitting machine. A clamp 13, pivotally attached to the bar 10, by a pin 14, serves as a means for securing such bar to the knife beam upon manual operation of the hand screw 15, said screw being threaded through a hole provided in a block 16 which is bolted to the end of the bar 10. The circular knife 17, having a thickness of 0.010-0.020 inch, and a metal backing disc 18 are clamped between an inner flange 19, formed integrally with the shaft 20, and an outer clamping washer 21 by a socket screw 22, FIG. 1. This assembly will be understood by reference to the enlarged, fragmentary sectional view of FIG. 5, wherein the knife 17 is shown in operative position with respect to a power-driven backup knife 25 having a tapered edge 26. It will be noted that the backing disc 18 has an inwardly tapered marginal face portion presented to the cutting knife and that the clamping washer 21 retains the marginal face portion of the cutting knife against the disc edge 24 and offset at an angle with respect to the median plane of the backing disc, thereby prestressing the cutting knife. A thin, flexible knife normally cannot be manufactured or mounted economically to run with a sidewise wobble of less than 0.005 inch. However, the relatively thick, rigid backing disc can be made and mounted so that the sidewise wobble is less than 0.0002 inch. In this arrangement, a commercially manufactured knife blade is forced to run with a minimum side wobble and a small amount of prestress. Therefore, the knife will operate in continuous contact with the edge of the backup knife with minimum overlap and with minimum potential of overriding such edge. The amount of knife overlap, and the initial lateral pressure applied to the cutting knife are individually adjustable by means which will be described herein below. The peripheral surface of the backing disc 18 is provided with a circular groove accommodating a ring 27 made of rubber or other resilient material, which ring serves to minimize the tendency of the foil to wrinkle at the slitting station and to rotate the cutting knife at a peripheral speed corresponding to the linear speed of the foil. The shaft 20 passes through an opening formed in the end of a cylindrical housing 28.

Referring now to FIG. 1, the described cylindrical housing 28 carries a pair of spaced ball bearings having their outer races press-fitted into appropriate circular channels formed in the inner wall of the housing. The shaft 20 passes through the bearings and is clamped to the inner races of the bearings by means of an axial bushing 31, end plate 32 and screw 33, the latter being threaded into a hole formed in the end of the shaft 20. The normally open end of this housing is closed by a plate 34 secured in position by the screws 36. It will be apparent that the cutting knife 17 is freely rotatable about the bearing axis.

The cylindrical housing 28 (FIGS. 1 and 2) forms part of a structure which includes a second cylindrical housing 37 and a downwardly extending lever 38, the housing 37 having a normally open end closed by the plate 39. The end portion of the lever 38 is positioned to strike against the end of an adjustable stop screw 40 having a threaded shank passing through a threaded hole formed in a forwardly extending post 41 (as viewed in FIG. 1), which post is formed integrally with a transverse block 42 secured in fixed position to a slide plate 43. A heavy spring 44 is compressed between the post 41 and the knurled head of the screw 40, thereby to retain the screw in a set position. The cylindrical housing 37, oriented at a right angle to the cylindrical housing 28, carries a pair of spaced ball bearings retained in place in a manner similar to the ball bearings carried by the cylindrical housing 28. The broken away portion of FIG. 3 shows one of the bearings 45 carried by the cylindrical housing 37. The inner races of the two bearings, disposed in the housing 37, are mechanically coupled to a shaft 47 by a bushing and end plate arrangement similar to that shown in the housing 28 of FIG. 1. An end of the shaft 47 is rigidly secured to the slide plate 43, it now being apparent that the cutting knife is freely rotatable about the axis of the shaft 47.

Referring to FIG. 3, the facing surfaces of the slide plate 43 and the dove-tailed mounting plate 10 have aligned, V-shaped channels formed therein, which channels accommodate a spacing rod 48 secured in place with respect to the slide plate by a roll pin 49. A washer 50 is secured to the end of the spacing rod by means of a cap screw 51, and an aligned cap screw 52 is carried by an end plate 53 secured to the mounting plate 10 by the screws 54 (see also FIG. 4). A spring 55 is compressed between the washer 50 and the end plate 54. Thus, the spring biases the spacing rod and the slide plate 43 in the direction of the calibrated, differential screw 56. The outer, reduced-diameter shank portion 57, of the screw 56, is provided with a relatively coarse thread and passes into a correspondingly threaded hole formed in an end block 58 which is secured to the end of the slide plate 43, whereas the enlarged diameter shank portion 59 is provided with a fine thread and passes through a correspondingly threaded hole formed in the end block 16 which is secured to the end of the mounting plate 10. As an example, the screw shank portion 59 may be provided with 50 threads per inch, whereby one revolution of the screw results in a 0.005 inch linear displacement of slide plate 43 relative to the mounting plate 10. Such displacement also is imparted to the cutting knife which is pivotally secured to the slide plate by the shaft 47.

As shown in FIG. 2, the slide plate 43 is clampingly secured to the mounting plate 10 by a threaded stud 61 threaded into a hole provided in the mounting plate and having a flat central portion slidable in an elongated slot 62 formed in the slide plate. An assembly of flat washers and spring washers is positioned between the slide plate and a nut 63 which is threaded on the stud. The spacing rod 48, visible in FIG. 3, lies to the right of the bolt 61 as viewed in the top plan view of FIG. 1. A set screw 65, FIG. 1, is threaded through a hole formed in the slide plate 43 and has an end engaging the underlying surface of the mounting plate. This set screw provides a means for setting the two spaced plates 43 and 10 in parallel planes, after which the nut 63, FIG. 2, is tightened on the stud 61 to provide a desired clamping pressure between each of these plates and the spacing rod. The linear displacement of the slide plate relative to the mounting plate, upon rotation of the differential screw 56, is limited by the axial extent of the elongated slot 62 formed in the slide plate.

As best seen by reference to FIGS. 2 and 3, an air cylinder 66 has one end secured to a block 67 and the other end passing through a clearance opening formed in the transverse block 42, said blocks being secured to the slide plate 43. The air cylinder is secured to the block 67 by screws, not shown. The piston 68, of the air cylinder, is connected to an L-shaped bracket 69 and a pin 72 pivotally couples the bracket to an arm 71 welded to the cylindrical housing 37. Air under pressure is applied to the air cylinder through a flexible hose connected to the cylinder at the end opposite the piston. In the absence of air pressure applied to the cylinder, a spring, disposed in the cylinder, biases the piston to the retracted position, causing the cylindrical housing 37, the lever 38 and the cutting knife to rotate about the shaft 47 seen in FIG. 3. This rotation corresponds to a clockwise rotation of the described assembly as viewed in FIG. 1, the axis of rotation being identified by the letter 'a' (FIG. 1). The extent of such clockwise rotation is limited by the backing disc 18 striking the L-shaped bracket 69, in which position the cutting knife is spaced from the backup knife so that a metal foil can be passed between the knives prior to placing the slitting machine in operation. When air pressure is applied to the air cylinder, the piston is driven outwardly of the cylinder and the cutting knife is moved to the position shown in FIG. 1, the counterclockwise rotation of the cutting knife about the axis 'a' being limited by the lever 38 striking the end of the stop screw 40. By adjusting the screw 40, the lateral pressure between the cutting knife and the cooperating edge of the backup knife (FIG. 5) can be set to a desired magnitude.

In setting up the machine for slitting foil of a given thickness, say, 0.002 inch, the described assemblage is clampingly secured to the knife beam 11 (FIG. 2) so that the cutting knife 17 (FIG. 5) is positioned to strike the peripheral surface of the backup knife 25. The differential screw 56 (FIG. 2) is adjusted carefully until the peripheral surface of the cutting knife engages the peripheral surface of the backup knife. The assemblage then is unclamped from the knife beam, moved to a position wherein the cutting knife just clears the edge 26 of the backup knife, after which the assemblage is again clamped to the knife beam. The differential screw 56, FIG. 2, again is adjusted to displace the slide plate 43 0.003 inch in the direction of the cutting knife, thereby establishing an overlap of 0.003 inch between the cutting knife and the backup knife. During this portion of the setting-up procedure, the stop screw 40, FIG. 1 has been threaded through the post 41 so that its end projects somewhat further from the post. Air under pressure now is applied to the air cylinder, whereby the lever 38 strikes the end of the screw 40, in which position the lever will occupy a position displaced clockwise from the illustrated position. The purpose of such preliminary setting of the screw 40 is to prevent the cutting knife from striking the cooperating edge of the backup knife with an excessive force. Now, the screw 40 is backed-off slowly until the cutting knife engages the edge 26, after which the screw is backed-off farther, thereby to apply a desired pressure between the cutting knife and the backup knife. The described adjustments of the cooperating knives is of particular advantage in slitting machines having a plurality of such cooperating knives. The individual adjustment of each cutting knife with respect to its associated backup knife eliminates the requirement from grinding the cutting knives to a precise, equal radius. This feature also permits the clamping of each cutting knife assemblage to a rigid knife beam anchored in fixed position to the machine frame, thereby eliminating undesirable variations in the preset overlapping of the knives during machine operation, which variations occur when the knife beam is mounted for two direction adjustment on the machine frame. Furthermore, the cutting knife assembly makes it possible to reduce the amount of knife overlap to that required only to shear the foil while, at the same time, providing the necessary pressure between the cutting knife and the associated backup knife. The backing disc and the prestressed condition of the cutting knife prevent the knife from riding up onto the peripheral surface of the backup knife even under high speed machine operation.

Claims

Having now described the invention, what I desire to protect by Letters Patent is set forth in the following claims.

1. An assemblage for use in a foil-slitting machine and comprising,

a. a circular cutting knife,

b. a circular backing disc having a diameter less than that of the cutting knife, one face of the disc consisting of a central surface portion parallel to the median plane of the disc and a tapered marginal surface portion extending inwardly from an edge of the disc,

c. means securing the cutting knife to the backing disc, said means including a clamping member retaining the central portion of the cutting knife in flush contact with the said central surface portion of the backing disc and with a marginal face portion of the cutting knife in pressure contact with the said edge of the disc,

d. means mounting the cutting knife and backing disc for free rotation about a first axis normal to the median plane of the backing disc, and

e. means mounting the cutting knife and backing disc for pivotal movement about a second axis normal to the said first axis.

2. The invention as recited in claim 1, including a circular groove formed in the peripheral surface of the backing disc, and a ring of resilient material carried in the groove and extending radially outward therefrom.

3. An assemblage for use in a foil-slitting machine having a knife beam, which assemblage comprises,

a. a mounting plate removably securable to the knife beam,

b. a slideplate carried by the mounting plate,

c. manually operable means for displacing the slide-plate relative to the mounting plate,

d. a rotatable member carried by the slideplate and rotatable about a first axis normal to the plane of the slideplate,

e. a backing disc,

f. a circular cutting knife,

g. means securing the backing disc and the cutting knife to a shaft,

h. means carried by said rotatable member and supporting said shaft for rotation about an axis normal to the said first axis and parallel to the plane of the slideplate,

i. actuating means mechanically coupled to said rotatable member, actuation of said actuating means rotating the rotatable member about its axis, and

j. cooperating stop means carried by the slideplate and the rotatable member to limit rotation of the latter upon actuation of the actuating means.

4. The invention as recited in claim 3, wherein said actuating means is an air cylinder carried by the slideplate and having a piston coupled to the said rotatable member, and wherein said cooperating stop means comprises a lever carried by the rotatable member and an adjustable screw carried by the slideplate.

5. The invention as recited in claim 3, wherein the backing disc includes a tapered surface portion extending inwardly from an edge of the disc, and including means retaining the marginal portion of the knife face in pressure contact with the said edge of the disc and offset with respect to the median plane of the backing disc.

6. The invention as recited in claim 5, including a circular groove formed in the peripheral surface of the backing disc, and a ring of resilient material disposed in said groove and extending beyond the peripheral surface of the backing disc.

7. The invention as recited in claim 3, wherein the manually operable means for displacing the slideplate relative to the mounting plate comprises a first block secured to an end of the mounting plate, a second block secured to the proximate end of the slideplate, and a screw having a first threaded portion passing through a threaded hole formed in the said first block and a second threaded portion passing into a threaded hole formed in the said second block, the threaded portions of the screw having different threads.

8. In a foil-slitting machine of the class having a circular cutting knife carried by a knife beam and cooperating with a backup knife carried by a driven shaft, the improvement comprising,

a. a mounting plate removably secured to the knife beam,

b. a slideplate carried by the mounting plate,

c. manually operable means for displacing the slideplate with respect to the mounting plate and in a direction substantially normal to the axis of said shaft,

d. a rotatable member carried by the slideplate and rotatable about an axis normal to the plane of the slideplate,

e. a backing disc having a diameter less than that of the cutting knife, a face of said disc having a tapered surface portion extending inwardly from an edge of the disc,

f. means securing the cutting knife to the backing disc with a marginal face portion of the cutting knife in pressure contact with said edge of the disc and offset with respect to the median plane of the backing disc,

g. means carried by the said rotatable member and mounting the cutting knife and the backing disc for free rotation about an axis normal to that of the rotatable member,

h. means normally biasing said rotatable member in one direction to space the cutting knife from the backup knife,

i. actuating means for rotating said rotatable member in the other direction, and

j. adjustable stop means limiting rotation of said rotatable member in said other direction.

9. The invention as recited in claim 8, wherein the said actuating means comprises an air cylinder carried by the slideplate and having a piston mechanically coupled to said rotatable member, and wherein said adjustable stop means comprises a lever carried by the rotatable member and an adjusting screw carried by the slideplate and lying in the path of travel of the said lever.